Method and Apparatus for Carrier Aggregation

ABSTRACT

A method including: using first information and second information to determine a code book size, said first information including information for at least one first subframe of at least one cell for which feedback information is to be provided, said at least one first subframe is prior to subframe n and second information for at least one second subframe of at least one cell for which feedback information is to be provided, said at least one second subframe being after said subframe n; and using said code book size for providing feedback information.

This disclosure relates to a method and apparatus and in particular butnot exclusively to methods and apparatus for use with time divisionduplexing carrier aggregation.

A communication system can be seen as a facility that enablescommunication sessions between two or more nodes such as fixed or mobiledevices, machine-type terminals, access nodes such as base stations,servers and so on. A communication system and compatible communicatingentities typically operate in accordance with a given standard orspecification which sets out what the various entities associated withthe system are permitted to do and how that should be achieved. Forexample, the standards, specifications and related protocols can definethe manner how devices shall communicate, how various aspects ofcommunications shah be implemented and how devices for use in the systemshall be configured.

A user can access the communication system by means of an appropriatecommunication device. A communication device of a user is often referredto as user equipment (UE) or terminal. A communication device isprovided with an appropriate signal receiving and transmittingarrangement for enabling communications with other parties. Typically adevice such as a user equipment is used for enabling receiving andtransmission of communications such as speech and content data.

Communications can be carried on wireless carriers. Examples of wirelesssystems include public land mobile networks (PLMN) such as cellularnetworks, satellite based communication systems and different wirelesslocal networks, for example wireless local area networks (WLAN). Inwireless systems a communication device provides a transceiver stationthat can communicate with another communication device such as e.g. abase station of an access network and/or another user equipment. The twodirections of communications between a base station and communicationdevices of users have been conventionally referred to as downlink anduplink. Downlink (DL) can be understood as the direction from the basestation to the communication device and uplink (UL) the direction fromthe communication device to the base station.

Some systems use FDD (frequency division duplexing) and other systemsuse TDD (time division duplexing). With FDD, different frequencies areused for UL and DL communications with a UE. With TDD, the samefrequency is used for UL and DL communications but different time slotsare allocated for UL and DL communication.

Carrier aggregation has been proposed and this allows the bandwidthassociated with a UE to be expanded by concurrently using radioresources across two or more carriers. The component carriers areaggregated to form a larger overall transmission bandwidth

Control information may be communicated for example on a physical uplinkcontrol channel (PUCCH). For example, signaling for the purposes oferror detection and/or correction may be provided by means of suchsignaling. Requests for retransmission of any information that therecipient node did not successfully receive are possible. For example,hybrid automatic repeat request (HARQ) error control mechanism may beused for this purpose. The error control mechanism can be implementedsuch that a transmitting device shall receive either a positive or anegative acknowledgement (ACK/NACK; A/N) or other indication regardingits transmission from a receiving device.

UL control information may be communicated on a physical uplink sharedchannel (PUSCH) if the PUSCH is scheduled for UL data transmission.

HARQ can be used in the context of carrier aggregation (CA). Asmentioned previously, in carrier aggregation more than one carrier canbe used for communications between two devices. HARQ feedback for onecarrier may be transmitted on the Physical Uplink Control Channel(PUCCH) of another carrier.

Inter band TDD (time division duplex) CA with different UL DLconfigurations on the different bands has been proposed. This may causecomplexities with respect to HARQ feedback because HARQ timing in TDD iscoupled to the UL/DL configuration.

In a first aspect there is provided a method comprising: using firstinformation and second information to determine a code book size, saidfirst information comprising information for at least one first subframeof at least one cell for which feedback information s to be provided,said at least one first subframe is no later than subframe n and secondinformation for at least one second subframe of at least one call forwhich feedback information is to be provided, said at least one secondsubframe being after said subframe n; and using said code book size forproviding feedback information.

Preferably the method comprises receiving said first information andsaid second information from a base station.

Alternatively the method comprises receiving said first information froma base station and calculating said second information.

Preferably the method comprises receiving said information from saidbase station in a downlink assignment index contained in uplink grant.

Preferably the method comprises causing said feedback information to betransmitted on a physical uplink shared channel scheduled in subframe n.

Preferably the method comprises causing feedback information to betransmitted in a subframe which is k subframes later than subframe n.

Preferably said feedback information comprises feedback information forsaid at least one first subframe and said at least one second subframe,if said at least one second subframe is scheduled.

Preferably said at least one second subframe is not scheduled, then adiscontinuous transmission is provided for said at least one subframe assaid feedback information.

Preferably said feedback information comprises hybrid automatic repeatrequest information.

Preferably said first and second information comprises information froma plurality of different cells.

Preferably said plurality of different cells use different uplinkdownlink time division duplex configurations.

In a second aspect there is provided a method comprising: causing firstinformation and second information to be provided to a user equipment,said first and second information for determining a code book size, saidfirst information comprising information for at least one first subframeof at least one cell for which feedback information is to be provided,said at least one first subframe is no later than subframe n and secondinformation for at least one second subframe of at least one cell forwhich feedback information is to be provided, said at least one secondsubframe being after said subframe n.

In a third aspect there is provided a computer program comprisingcomputer executable instructions which when run are configured toprovide the method as set forth above.

In a fourth aspect there is provided an apparatus comprising at leastone processor and at least one memory including computer code for one ormore programs, the at least one memory and the computer code configured,with the at least one processor, to cause the apparatus at least to: usefirst information and second information to determine a code book size,said first information comprising information for at least one firstsubframe of at least one cell for which feedback information is to beprovided, said at least one first subframe is no later than subframe nand second information for at least one second subframe of at least onecell for which feedback information is to be provided, said at least onesecond subframe being after said subframe n; and use said code book sizefor providing feedback information.

Preferably the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to receive saidfirst information and said second information from a base station.

Alternatively the at least one memory and the computer code areconfigured with the at least one processor to cause the apparatus toreceive said first information from a base station and calculate saidsecond information.

Preferably the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to receive saidinformation from said base station in an uplink downlink assignmentindex.

Preferably the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to cause saidfeedback information to be transmitted on a physical uplink sharedchannel scheduled in subframe n.

Preferably the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to cause feedbackinformation to be transmitted in a subframe which is k subframes laterthan subframe n.

Preferably said feedback information comprises feedback information forsaid at least one first subframe and said at least one second subframe,if said at least one second subframe is scheduled.

Preferably the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to, if said atleast one second subframe is not scheduled, to provide a discontinuoustransmission for said at least one subframe as said feedbackinformation.

Preferably said feedback information comprises hybrid automatic repeatrequest information.

Preferably said first and second information comprises information froma plurality of different cells.

Preferably said plurality of different cells use different uplinkdownlink time division duplex configurations.

In a fifth aspect there is provided a user equipment comprising anapparatus as set forth above.

In a sixth aspect there is provided an apparatus comprising at least oneprocessor and at least one memory including computer code for one ormore programs, the at least one memory and the computer code configured,with the at least one processor, to cause the apparatus at least to:cause first information and second information to be provided to a userequipment, said first and second information for determining a code booksize, said first information comprising information for at least onefirst subframe of at least one cell for which feedback information is tobe provided, said at least one first subframe is no later than subframen and second information for at least one second subframe of at leastone cell for which feedback information is to be provided, said at leastone second subframe being after said subframe n.

In a seventh aspect there is provided a base station comprising anapparatus as set forth above.

In an eighth aspect there is provided a method comprising: causing firstinformation to be provided to a user equipment, said first informationfor determining a code book size, said first information comprisinginformation for at least one first subframe of at least one call forwhich feedback information is to be provided, said at least one firstsubframe is no later than subframe n and second information for at leastone second subframe of at least one cell for which feedback informations to be provided, said at least one second subframe being after saidsubframe n.

In a ninth aspect there is provided an apparatus comprising at least oneprocessor and at least one memory including computer code for one ormore programs, the at least one memory and the computer code configured,with the at least one processor, to cause the apparatus at least to:cause first information to be provided to a user equipment, said firstinformation for determining a code book size, said first informationcomprising information for at least one first subframe of at least onecell for which feedback information s to be provided, said at least onefirst subframe is no later than subframe n and second information for atleast one second subframe of at least one cell for which feedbackinformation is to be provided, said at least one second subframe beingafter said subframe n.

In a tenth aspect there is provided an apparatus comprising means forusing first information and second information to determine a code booksize, said first information comprising information for at least onefirst subframe of at least one cell for which feedback information is tobe provided, said at least one first subframe is no later than subframen and second information for at least one second subframe of at leastone cell for which feedback information is to be provided, said at leastone second subframe being after said subframe n; and means for usingsaid code book size for providing feedback information.

Preferably the apparatus comprises means for receiving said firstinformation and said second information from a base station.

Alternatively the apparatus comprising means for receiving said firstinformation from a base station and means for calculating said secondinformation.

Preferably the apparatus is configured to receive said information fromsaid base station in an uplink downlink assignment index.

Preferably the apparatus is configured to cause said feedbackinformation to be transmitted on a physical uplink shared channelscheduled in subframe n.

Preferably the apparatus is configured to cause feedback information tobe transmitted in a subframe which is k subframes later than subframe n.

Preferably said feedback information comprises feedback information forsaid at least one first subframe and said at least one second subframe,if said at least one second subframe is scheduled.

Preferably the apparatus comprises means for, if said at least onesecond subframe is not scheduled, providing a discontinuous transmissionfor said at least one subframe as said feedback information.

Preferably said feedback information comprises hybrid automatic repeatrequest information.

Preferably said first and second information comprises information froma plurality of different cells.

Preferably said plurality of different cells use different uplinkdownlink time division duplex configurations.

In an eleventh aspect there is provided a user equipment comprising anapparatus as set forth above.

In a twelfth aspect there is provided an apparatus comprising means forcausing first information and second information to be provided to auser equipment, said first and second information for determining a codebook size, said first information comprising information for at leastone first subframe of at least one cell for which feedback informationis to be provided, said at least one first subframe is no later thansubframe n and second information for at least one second subframe of atleast one cell for which feedback information is to be provided, said atleast one second subframe being after said subframe n.

In a thirteenth aspect there is provided a base station comprising anapparatus as set forth above.

In a fourteenth aspect there is provided an apparatus comprising meansfor causing first information to be provided to a user equipment, saidfirst information for determining a code book size, said firstinformation comprising information for at least one first subframe of atleast one cell for which feedback information is to be provided, said atleast one first subframe is no later than subframe n and secondinformation for at least one second subframe of at least one cell forwhich feedback information is to be provided, said at least one secondsubframe being after said subframe n.

A node such as a base station or a communication device of a user ofmachine type terminal can be configured to operate in accordance withthe various embodiments.

A computer program comprising program code means adapted to perform themethod may also be provided. The computer program may be stored and/orotherwise embodied by means of a carrier medium.

It should be appreciated that any feature of any aspect may be combinedwith any other feature of any other aspect.

Embodiments will now be described in further detail, by way of exampleonly, with reference to the following examples and accompanyingdrawings, in which:

FIG. 1 shows a schematic diagram of a communication system comprising abase station and a plurality of communication devices;

FIG. 2 shows a schematic diagram of a mobile communication deviceaccording to some embodiments;

FIG. 3 shows a schematic diagram of a control apparatus according tosome embodiments;

FIG. 4 shows a table of uplink and downlink configuration options forLTE TDD;

FIG. 5 shows a table for the report of HARQ feedback for each of theconfiguration options of FIG. 4;

FIG. 6 shows a first problem with configurations 1 and 5 when used inCA;

FIG. 7 shows a second problem with configurations 6 and 3 when used inCA;

FIG. 8 shows a table with “k” values for the TDD configurations of FIG.4; and

FIG. 9 shows how embodiments address the problem with configurations 1and 5 shown in FIG. 6.

In the following certain exemplifying embodiments are explained withreference to a wireless or mobile communication system serving mobilecommunication devices. Before explaining in detail the exemplifyingembodiments, certain general principles of a wireless communicationsystem, access systems thereof, and mobile communication devices arebriefly explained with reference to FIGS. 1 to 3 to assist inunderstanding the technology underlying the described examples.

An example of wireless communication systems are architecturesstandardized by the 3rd Generation Partnership Project (3GPP). A latest3GPP based development is often referred to as the long-term evolution(LTE) of the Universal Mobile Telecommunications System (UMTS)radio-access technology. The various development stages of the 3GPP LTEspecifications are referred to as releases. More recent developments ofthe LTE are often referred to as LTE Advanced (LTE-A). The LTE employs amobile architecture known as the Evolved Universal Terrestrial RadioAccess Network (E-UTRAN). Base stations of such systems are known asevolved or enhanced Node Bs (eNBs) and may provide E-UTRAN features suchas user plane Radio Link Control/Medium Access Control/Physical layerprotocol (RLC/MAC/PHY) and control plane Radio Resource Control (RRC)protocol terminations towards the communication devices. Other examplesof radio access system include those provided by base stations ofsystems that are based on technologies such as wireless local areanetwork (WLAN) and/or WiMax (Worldwide Interoperability for MicrowaveAccess).

A device capable of wireless communications can communicate via at leastone base station or similar wireless transmitter and/or receiver node.In FIG. 1 a base station 10 is shown to be serving various mobiledevices 20 and a machine-like terminal 22. Base stations are typicallycontrolled by at least one appropriate controller apparatus so as toenable operation thereof and management of mobile communication devicesin communication with the base stations. The base station can beconnected further to a broader communications system 12. It shall beunderstood that a number of neighbouring and/or overlapping accesssystems or radio service areas provided by a number of base stations mayexist. A base station site can provide one or more cells or sectors,each sector providing a cell or a subarea of a cell. Each device andbase station may have one or more radio channels open at the same timeand may send signals to and/or receive signals from one or more sources.As a plurality of devices can use the same wireless resource,transmissions thereof need to be scheduled to avoid collisions and/orinterference.

A possible mobile communication device for transmitting in uplink andreceiving in downlink will now be described in more detail withreference to FIG. 2 showing a schematic, partially sectioned view of acommunication device 20. Such a communication device is often referredto as user equipment (UE) or terminal. An appropriate communicationdevice may be provided by any device capable of sending radio signals toand/or receiving radio signals. Non-limiting examples include a mobilestation (MS) such as a mobile phone or what is known as a ‘smart phone’,a portable computer provided with a wireless interface card or otherwireless interface facility, personal data assistant (PDA) provided withwireless communication capabilities, or any combinations of these or thelike. A mobile communication device may provide, for example,communication of data for carrying communications such as voice,electronic mail (email), text message, multimedia and so on. Users maythus be offered and provided numerous services via their communicationdevices. Non-limiting examples of these services include two-way ormulti-way calls, data communication or multimedia services or simply anaccess to a data communications network system, such as the Internet.Non-limiting examples of content data include downloads, television andradio programs, videos, advertisements, various alerts and otherinformation.

The device 20 is configured to receive signals in the downlink 29 overan air interface via appropriate apparatus for receiving and to transmitsignals in the uplink 28 via appropriate apparatus for transmittingradio signals. In FIG. 2 the transceiver apparatus is designatedschematically by block 26. The transceiver apparatus 26 may be providedfor example by means of a radio part and associated antenna arrangement.The antenna arrangement may be arranged internally or externally to themobile device.

A mobile communication device is also provided with at least one dataprocessing entity 21, at least one memory 22 and other possiblecomponents 23 for use in software and hardware aided execution of tasksit is designed to perform, including control of access to andcommunications with base stations and/or other communication devices.The data processing storage and other relevant apparatus can be providedon an appropriate circuit board and/or in chipsets. This apparatus isdenoted by reference 24.

The user may control the operation of the mobile device by means of asuitable user interface such as key pad 25, voice commands, touchsensitive screen or pad, combinations thereof or the like. A display 27,a speaker and a microphone can be also provided. Furthermore, acommunication device may comprise appropriate connectors (either wiredor wireless) to other devices and/or for connecting externalaccessories, for example hands-free equipment, thereto.

FIG. 3 shows an example of a control apparatus 30 for a communicationsystem, for example to be coupled to and/or for controlling a basestation. In some embodiments a base station may comprise an integratedcontrol apparatus and some other embodiments the control apparatus canbe provided by a separate network element. The control apparatus can beinterconnected with other control entitles. The control apparatus andfunctions may be distributed between a plurality of control units. Insome embodiments each base station can comprise a control apparatus. Inalternative embodiments, two or more base stations may share a controlapparatus. The arrangement of the control depends on the standard, andfor example in accordance with the current LTE specifications noseparate radio network controller is provided. Regardless of thelocation, the control apparatus 30 can be understood as providingcontrol on communications in the service area of at least one basestation. The control apparatus 30 can be configured to provide controlfunctions in accordance with embodiments described below. For thispurpose the control apparatus can comprise at least one memory 31, atleast one data processing unit 32, 33 and an input/output interface 34.Via the interface the control apparatus can be coupled to a base stationor other parts of the base station to cause operation of the basestation in accordance with the below described embodiments. The controlapparatus can be configured to execute an appropriate software code toprovide the control functions.

A wireless communication device, such as a mobile device, machine-liketerminal or a base station, can be provided with a MultipleInput/Multiple Output (MIMO) antenna system. MIMO arrangements as suchare known. MIMO systems use multiple antennas at the transmitter andreceiver along with advanced digital signal processing to improve linkquality and capacity. For example, the transceiver apparatus 26 of FIG.2 can provide a plurality of antenna ports. More data can be receivedand/or sent where there are more antennae elements.

Some embodiments may be used in relation to 3GPP LTE-Advanced technologyRel-11. It should of course be appreciated that some embodiments may beused with later releases or in relation to different standards. Someembodiments may be used with the LTE TDD carrier aggregation (CA)enhancement of different TDD UL/DL configurations on different bands.

Inter-band TDD CA (carrier aggregation) with different UL/DLconfigurations on different bands has been proposed. Some embodimentsrelates to HARQ-ACK feedback on the PUCCH and/or PUSCH.

With inter-band TDD CA, different UL/DL configurations may be used ondifferent carriers (cells). Inter band carrier aggregation of TDDcomponent carriers with different uplink/down link configurations maygive rise to certain advantages. For example, these advantages mayinclude one or more of the following: coexistence with the neighbouringlegacy TDD systems; supporting aggregation of traffic dependent carriersin heterogeneous networks; flexible configuration, for example moreuplink subframes in the lower frequency bands for better coverage and/ormore downlink subframes in high frequency bands for traffictransmission; and/or obtain a higher peak data rate.

LTE TDD allows for asymmetric uplink/downlink allocation by providingseven different TDD uplink/down link configurations. This is shown intable of FIG. 4. These configurations may provide for example between 40to 909 down link frames. There are configurations 0-6. Eachconfiguration specifies which of ten subframes 0-9 are uplink subframesand which are downlink subframes. In some embodiments, subframes 0 and 5contain a synchronization signal and broadcast information which allowsthe UE to perform synchronization and obtain relevant systeminformation. These subframes are downlink subframes. Subframe 1 is asubframe which serves as a switching point between downlink to uplinktransmissions. This has a downlink pilot time slot and an uplink pilottime slot separated by a guard period. Depending on the switching pointperiodicity, in some UL/DL configurations subframe 6 may also serve as aswitching point. In configuration number 0 (#0), subframes 2, 3, 4, 7, 8and 9 are uplink subframes.

LTE TDD may be operated as a DL heavy system, which results in a ULsubframe often used to transmit HARQ-ACKs corresponding to multiple DLsubframes. As for example specified in TS 36.213, the set of DLsubframes whose HARQ-ACKs are reported in the same UL subframe is listedin the Table of FIG. 5. The table of FIG. 5 shows which uplink subframeshandling ACK/NACK feedback for certain downlink subframe(s) for each ofthe different UL/DL configurations of FIG. 4. For example, in UL/DLconfiguration #4, uplink subframe #2 handles feedback for downlinksubframes which are 12, 8, 7, and 11 subframes earlier than uplinksubframe 2, i.e. downlink subframes 0, 4, 5, and 1. Depending on theuplink-downlink configuration one uplink subframe may be responsible forACK/NACK feedback for one or multiple downlink subframes. This meansthat HARQ feedback on different carriers may follow different timings.

It has been agreed that HARQ-ACK timing of PCell (primary cell) PDSCH(physical downlink shared channel), the scheduling timing of PCellPUSCH, and the HARQ timing of PCell PUSCH should follow the PCelltiming. The PCell timing may be as in Rel-8/9/10.

It has been agreed that the PDSCH HARQ timing on SCell (secondary cell)shall follow the PCell SIB1 (System Information Block) configuration ifthe set of DL subframes indicated by the SCell SIB1 configuration is asubset of the DL subframes indicated by the PCell SIB1 configuration.

For the case where the set of DL subframes indicated by the SCell SIB1configuration is not a subset of the DL subframes indicated by the PCellSIB1 configuration the following has been decided for a self-schedulingsituation (Self-scheduling means that the grant for PDSCH/PUSCH on cellc is transmitted on cell c)).

On PDSCH timing for the case where the SCell(s) downlink subframes is asuperset of PCell, for a full-duplex case, agreement is that SCell PDSCHHARQ timing should follow the SCell SIB1 HARQ timing. For a half-duplexcase, the assumption is to follow SCell SIB1 HARQ timing

On PDSCH timing for the case where the set of SCell(s) downlinksubframes is neither a subset nor a superset of PCell, in the case ofself-scheduling, a reference configuration is used where the timingfollows a third UL/DL configuration (different than PCell and SCell SIB1UL/DL configuration).

Based on the above, PDSCH HARQ timing for PCell PDSCH follows PCellUL/DL configuration itself, while PDSCH HARQ timing reference for aSCell in case of self-scheduling and full duplex follows the HARQ timingreference for a SCell.

The HARQ timing reference for a SCell can be different from PCell TDDUL/DL configuration. As a result, the inventors have appreciated thatthe HARQ-ACK transmission methods defined in Rel-10 assuming PCelltiming for all configured carriers are problematic.

As shown in FIG. 6, two carriers on different bands with different TDDUL/DL configurations are aggregated. PCell Is configured with TDD UL/DLconfiguration number 1 and SCell with TDD UL/DL configuration number 5.Therefore, the set of DL subframes on SCell is a superset of the DLsubframes on PCell. PDSCH HARQ timing for PCell PDSCH shall follow TDDUL/DL configuration 1, while PDSCH HARQ timing reference for the SCellin case of self-scheduling shall follow TDD UL/DL configuration 5.

Therefore, according to the ACK/NACK transmission timing specified inthe table of FIG. 5, ACK/NACK corresponding to DL subframe 5 and 6 inthe PCell should be transmitted In UL subframe 2 in the PCell to followthe HARQ timing of TDD UL/DL configuration 1. Meanwhile, ACK/NACKcorresponding to DL subframe 9 (in previous frame) and DL subframes inthe subframes 0 to 8 (in current frame) in the SCell shall betransmitted in UL subframe 2 (in next frame) in the PCell to follow theHARQ timing of TDD UL/DL configuration 5. When these ACK/NACK bits aretransmitted by PUSCH in UL subframe Z in PCell and this PUSCH isadjusted based on a detected PDCCH with DCI (downlink controlinformation) format 0/4, this DCI format 0/4 should be sent in DLsubframe 6 in the PCell following PCell PUSCH transmission timing inFIG. 8. In this way, eNB does not know whether SCell DL subframe 7 and 8will be scheduled or not due to UL grant timing in PCell is prior tothese two subframes possibly being scheduled in the SCell in the timedomain. If the eNB still sends the DAI (downlink assignment index) inDCI format 0/4 according to the maximum scheduled DL subframes acrossthe two carriers without the consideration of DL subframe 7 and 8possibly being scheduled in the SCell, UE shall get a wrong UL DAI incase of DL subframe 7 and 8 in SCell are scheduled. Since UL DAI is usedto determine the codebook size of HARQ-ACK transmission it will lead todifficulties with the ACK/NACK feedback between eNB and UE.

The UL DAI indicates the number of bits the UE is required to feedback.The DL DAI indicates to the UE the number of subframes scheduled up tothe detected DL grant.

A similar case is shown n FIG. 7 when the PCell is configured with TDDUL/DL configuration #6 and SCell with TDD UL/DL configuration #3 asshown in FIG. 3. In this case, the set of DL subframes on SCell Is alsoa superset of the DL subframes on the PCell. The PDSCH HARQ timing forPCell PDSCH shall follow TDD UL/DL configuration 6, while the PDSCH HARQtiming reference for the SCell in case of self-scheduling shall followTDD UL/DL configuration 3.

Therefore, according to the ACK/NACK transmission timing specified inthe table of FIG. 5, an ACK/NACK corresponding to DL subframe 5 and 6 inPCell shall be transmitted in UL subframe 2 and 3 respectively in thePCell to follow the HARQ timing of TDD UL/DL configuration 6. Meanwhile,the ACK/NACK corresponding to DL subframe 1, 5 and 6 In the SCell shallbe transmitted in UL subframe 2 In the PCell, and the ACK/NACKcorresponding to DL subframe 7 and 8 in SCell shall be transmitted in ULsubframe 3 in PCell to follow the HARQ timing of TDD UL/DL configuration3. When these ACK/NACK bits are transmitted by the PUSCH and the PUSCHis adjusted based on a detected PDCCH with DCI format 0/4, this DCIformat 0/4 should be sent in DL subframe 5 and 6 In the PCell followingthe PCell PUSCH transmission timing, respectively. In this way, in DLsubframe 5, the eNB does not know whether the SCell DL subframe 6 willbe scheduled or not due to UL grant timing in the PCell prior to onesubframe possibly being scheduled in the SCell in the time domain. In DLsubframe 6, a eNB does not know whether the SCell DL subframe 7 and 8will be scheduled or not due to UL grant timing in the PCell prior tothese two subframes possibly being scheduled in the SCell in the timedomain. This may lead to difficulties with ACK/NACK codebook sizebetween eNB and UE.

It is noted that in FIG. 7 the number of possibly scheduled DL subframesin SCell later than the UL grant in PCell is different in different setsof DL subframes whose HARQ-ACKs are reported in the same UL subframe.

Based on the above, different PDSCH HARQ reference timings may be usedfor inter-band TDD CA with different TDD UL/DL configurations. Theresults in different bundle window sizes. The bundle window size is thenumber of elements in the set Kc. For example, for configuration 0 oneUL subframe is used for HARQ feedback for only 1 DL subframe, M=1 oronly 1 element in the set Kc. For other configurations, such asconfiguration 2, UL subframe#2 is used for HARQ feedback for 4 DLsubframes, in this case M=4 or 4 elements in the set Kc. The differentbundle window sizes may lead to the problems with the UL DAI when theHARQ-ACK is transmitted on the PUSCH adjusted by DCI format 0/4. Sincethe codebook size is determined by UL DAI, this issue may cause amisunderstanding on the ACK/NACK transmission between eNB and UE. The DLperformance may be degraded. Some embodiments address this UL DAI.

Currently for TDD, upon detection of a PDSCH transmission or a PDCCHindicating downlink SPS (semi persistent scheduling) release withinsubframe(s) n−k, where k∈K and K is defined in the table of FIG. 5intended for the UE and for which ACK/NACK response shall be provided,the UE will transmit the ACK/NACK response in UL subframe n.

For TDD UL/DL configurations 1-6 and normal HARQ operation, the UE will,upon detection of a PDCCH with uplink DCI format and/or a PHICH(Physical hybrid ARQ indicator channel) transmission in a subframe nintended for the UE, adjust the corresponding PUSCH transmission insubframe n+k, with k given in the table of FIG. 8, according to thePDCCH and PHICH information.

In LTE Rel-10 CA, all configured component carriers are configured withsame TDD UL/DL configurations. So the bundle window sizes in PCell andSCell are always same.

The inventors have appreciated that the proposals in LTE Rel-11inter-band TDD CA, different PDSCH HARQ reference timing used withdifferent TDD UL/DL configurations and that this causes different bundlewindow sizes. This leads to difficulties with the UL DAI indication.

In some embodiments, an UL DAI indication/ACK/NACK codebook sizedetermination scheme is provided for an inter-band TDD CA UE configuredwith different TDD UL/DL configurations on different bands.

In some embodiments two types of DL subframes can be defined:

DL subframes on all serving cells no later than the DL subframe n andthe corresponding ACK/NACK transmitted on the PUSCH scheduled in DLsubframe n are referred to as type 1;

DL subframes on all serving cells later than the DL subframe n and thecorresponding ACK/NACK transmitted on PUSCH scheduled in DL subframe nare referred to as type 2.

ACK/NACK corresponding to both types of DL subframes are reported in thesame UL subframe n+k, where k is given in the table of FIG. 8, accordingto the PDCCH information.

In a first embodiment, the UE generates ACK/NACK codebook on PUSCHaccording to UL DAI, but the value of UL DAI calculated at the eNB sideshould be the maximum number of actually scheduled type 1 DL subframesplus a maximum number of type 2 DL subframes. A new definition of the ULDAI may be specified so that the UE does not interpret the UL DAI bye.g. take non-scheduling as DL grant missing, or determine a wrongcodebook size.

In a second embodiment, the UE generates a ACK/NACK codebook on thePUSCH according to UL DAI and the maximum number of type 2 DL subframes,and the value of the UL DAI calculated at the eNB side should be themaximum number of actually scheduled type 1 DL subframes. The requiresthe specifying of new codebook generation at UE side.

For either or both of these embodiments, if the UE does not detect anyDL PDSCH transmission or PDCCH indicating DLSPS release in a type 2 DLsubframe, the LIE shall feedback DTX (discontinuous transmission) asHARQ-ACK transmission corresponding to that subframe.

Hence, the corresponding ACK/NACK feedback can be transmitted on PUSCHafter detected DCI format 0/4. Any misunderstanding on the codebook sizedetermination between eNB and UE can be avoided.

These embodiments will now be described in more detail.

To summarize, in LTE Rel-11 inter-band TDD CA with different TDD UL/DLconfigurations on different bands, because different PDSCH HARQreference timing may be used for different carriers, the bundle windowsize of PCell and SCell may be different, which will lead to thedifficulties in relation to the UL DAI when the HARQ-ACK is transmittedon PUSCH adjusted by DCI format 0/4.

Reference is made to FIG. 9 which shows how some embodiments may addressthe problem set out in relation to FIG. 6.

The DL subframe 5 and 6 In the PCell and the DL subframe 9 (In theprevious frame) and the DL subframes 0 to 6 (in current frame) in theSCell are type 1 DL subframes, and the DL subframe 7 and 8 in the SCellare type 2 DL subframes, corresponding to the PUSCH on the PCellscheduled in the DL subframe 6 in the PCell.

Assume the DL subframe 5 and 6 in PCell together with DL subframe 0, 4,5 and 6 In SCell are scheduled. According to the HARQ transmissiontiming specified in the table of FIG. 5, ACK/NACK corresponding to theseDL subframes in the PCell and the SCell shall be transmitted in ULsubframe 2 In the PCell to follow the respective HARQ timing of TDDUL/DL configuration 1 and 5. When these ACK/NACK bits are transmitted byPUSCH in UL subframe 2 in PCell and this PUSCH is adjusted based on adetected PDCCH with DCI format 0/4, this DCI format 0/4 should be sentin DL subframe 6 in the PCell following PCell PUSCH transmission timing.

Hence, up to Subframe 6, the current maximum scheduled DL subframesacross PCell and SCell are 4 without the consideration of SCell DLsubframe 7 and 8. So W_(DAI) ^(UL)=4. With current specification, if eNBsends this DAI value in DCI format 0/4, the UE would get a wrong UL DAIin case of either DL subframe 7 or 8 or both are scheduled in the SCell,which will lead to misunderstanding on ACK/NACK codebook size betweeneNB and UE.

In the first embodiment, the DAI in DCI format 0/4 in PCell isdetermined by the current maximum practically scheduled DL subframesplus the number of possibly to be scheduled DL subframes in SCell laterthan the subframe for the sending DCI format 0/4 whose HARQ-ACKs arereported in the same UL subframe. In FIG. 9, this new DAI is 4+2=6. SoW_(DAI) ^(UL)=2 is sent in DCI format 0/4 from the base stationaccording to the equation of B_(c) ^(DL)=W_(DAI) ^(UL)+4┌(U−W_(DAI)^(UL))/4┐.

At UE side, upon detection of this DAI in DCI format 0/4, UE shall knowthe codebook size determination, O_(c) ^(ACK) for the c-th serving cell,where c≥0, O_(c) ^(ACK)=B_(c) ^(DL) if the transmission mode configuredin the c-th serving cell supports one transport block or spatialHARQ-ACK bundling is applied and O_(c) ^(ACK)=2B_(c) ^(DL) otherwise,where B_(c) ^(DL) is the number of downlink subframes for which the UEneeds to feedback HARQ-ACK bits for the c-th serving cell. In detail,for PCell configured with TDD UL/DL configuration 1, the UE shall assumeB_(c) ^(DL)=min(W_(DAI) ^(UL),M_(c))=2 for PCell and generate twoACK/NACK bits corresponding to DL subframe 5 and 6, o_(c,0) ^(ACK)o_(c,1) ^(ACK); for SCell configured with TDD UL/DL configurations 5,the UE shall B_(c) ^(DL)=W_(DAI) ^(UL)+4|(U−W_(DAI) ^(UL))/4|=6 andgenerate 6 ACK/NACK bits corresponding to DL subframe 0, 4, 5, 6, 7 and8, o_(c,0) ^(ACK) o_(c,1) ^(ACK), . . . , o_(c,5) ^(ACK) where U denotesthe maximum total number of received PDSCHs and PDCCH indicatingdownlink SPS release in subframe(s) n−k on the SCell, k∈K. If UE doesnot detect any DL PDSCH transmission or PDCCH indicating DL SPS releasein the SCell DL subframe 7 or 8, UE shall feedback DTX as HARQ-ACKtransmission corresponding to that subframe. Thus in some embodimentsthere is no misunderstanding between eNB and UE on ACK/NACK codebooksize determination.

With the second embodiment, the DAI in DCI format 0/4 in the PCell maybe determined by the current maximum practically scheduled DL subframes.In FIG. 9, this new DAI is 4. So W_(DAI) ^(UL)=4 is sent in DCI format0/4 according to the equation of B_(c) ^(DL)=W_(DAI) ^(UL)+4┌(U−W_(DAI)^(UL))/4┐.

At UE side, upon detection of this DAI in DCI format 0/4, UE shall knowthe codebook size determination, O_(c) ^(ACK) for the c-th serving cell,where c≥0, O_(c) ^(ACK)=B_(c) ^(DL) If transmission mode configured inthe c-th serving cell supports one transport block or spatial HARQ-ACKbundling is applied and O_(c) ^(ACK)=2B_(c) ^(DL) otherwise, where B_(c)^(DL) is the number of downlink subframes for which the UE needs tofeedback HARQ-ACK bits for the c-th serving cell. In detail, for PCellconfigured with TDD UL/DL configuration 1, the UE shall assume B_(c)^(DL)=min(W_(DAI) ^(UL),M_(c))=2 for PCell and generate two ACK/NACKbits corresponding to DL subframe 5 and 6, a o_(c,0) ^(ACK) o_(c,1)^(ACK); for SCell configured with TDD UL/DL configurations 5, the numberof possibly to be scheduled DL subframes in SCell later than thesubframe of sending DCI format 0/4 whose HARQ-ACKs are reported in thesame UL subframe is 2, so the UE shall assume B_(c) ^(DL)=W_(DAI)^(UL)+4┌(U−W_(DAI) ^(UL))/4┐+2=6 and generate 6 ACK/NACK bitscorresponding to DL subframe 0, 4, 5, 6, 7 and 8, o_(c,0) ^(ACK) o_(c,1)^(ACK) . . . , o_(c,5) ^(ACK) where U denotes the maximum total numberof received PDSCHs and PDCCH indicating downlink SPS release insubframe(s) n−k on the SCell, k∈K. If UE does not detect any DL PDSCHtransmission or PDCCH indicating DL SPS release in the SCell DL subframe7 or 8, UE shall feedback DTX as HARQ-ACK transmission corresponding tothat subframe. There is thus no misunderstanding between eNB and UE onACK/NACK codebook size determination.

Some embodiments may provide one or more of the following advantages:

-   -   (1) Inter-band TDD carrier aggregation with different TDD UL/DL        configurations on different bands may be implemented; and    -   (2) Misunderstandings between the eNB and the UE on ACK/NACK        codebook size determination may be avoided.

It is noted that whilst embodiments have been described in relation toLTE, similar principles can be applied to any other communication systemor to further developments with LTE. Thus, although the embodiments aredescribed with references to uplink and downlink, this disclosure is notlimited by these directions between a base station and a user terminal.Instead, the invention is applicable to any system with transmissionsbetween two or more communicating entities. For example, a communicationsystem may be provided by means of a plurality of user equipment, forexample in adhoc networks. Therefore, although certain embodiments weredescribed above by way of example with reference to certain exemplifyingarchitectures for wireless networks, technologies and standards,embodiments may be applied to any other suitable forms of communicationsystems than those illustrated and described herein.

The required data processing apparatus and functions of a base stationapparatus, a communication device and any other appropriate apparatusmay be provided by means of one or more data processors. The describedfunctions at each end may be provided by separate processors or by anintegrated processor. The data processors may be of any type suitable tothe local technical environment, and may include one or mare of generalpurpose computers, special purpose computers, microprocessors, digitalsignal processors (DSPs), application specific integrated circuits(ASIC), gate level circuits and processors based on multi core processorarchitecture, as non-limiting examples. The data processing may bedistributed across several data processing modules. A data processor maybe provided by means of, for example, at least one chip. Appropriatememory capacity can also be provided in the relevant devices. The memoryor memories may be of any type suitable to the local technicalenvironment and may be implemented using any suitable data storagetechnology, such as semiconductor based memory devices, magnetic memorydevices and systems, optical memory devices and systems, fixed memoryand removable memory.

In general, the various embodiments may be implemented in hardware orspecial purpose circuits, software, logic or any combination thereof.Some aspects of the invention may be implemented in hardware, whileother aspects may be implemented in firmware or software which may beexecuted by a controller, microprocessor or other computing device,although the invention is not limited thereto. While various aspects ofthe invention may be illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it is wellunderstood that these blocks, apparatus, systems, techniques or methodsdescribed herein may be implemented in, as non-limiting examples,hardware, software, firmware, special purpose circuits or logic, generalpurpose hardware or controller or other computing devices, or somecombination thereof. The software may be stored on such physical mediaas memory chips, or memory blocks implemented within the processor,magnetic media such as hard disk or floppy disks, and optical media suchas for example DVD and the data variants thereof, CD.

The foregoing description has provided by way of exemplary andnon-limiting examples a full and informative description of theexemplary embodiment of this invention. However, various modificationsand adaptations may become apparent to those skilled in the relevantarts in view of the foregoing description, when read in conjunction withthe accompanying drawings and the appended claims. However, all such andsimilar modifications of the teachings of this invention will still fallwithin the scope of this invention as defined in the appended claims.Indeed there is a further embodiment comprising a combination of one ormore of any of the other embodiments previously discussed.

1.-29. (canceled)
 30. A method comprising: using, by a user equipment,first information and second information to determine a code book sizefor an ACK/NACK codebook, the first information comprising informationabout at least one first subframe of at least one cell for whichfeedback information is to be transmitted, the at least one firstsubframe being no later than subframe n and the second informationcomprising information about at least one second subframe of at leastone cell for which feedback information is to be transmitted, the atleast one second subframe being after the subframe n; wherein the firstinformation and the second information together comprise informationabout a plurality of different cells, and wherein the plurality ofdifferent cells use different uplink downlink time division duplexconfigurations; and causing, by the user equipment, the feedbackinformation, based on the code book size, to be transmitted; wherein theACK/NACK codebook is generated according to a maximum number of actuallyscheduled type 1 downlink sub frames plus a maximum number of type 2downlink subframes, and wherein the type 1 downlink subframes comprisedownlink sub frames no later than the subframe n and a correspondingpositive or negative acknowledgement transmitted on a physical uplinkshared channel scheduled in the subframe n, and wherein the type 2downlink subframes comprise downlink subframes later than the subframe nand the corresponding positive or negative acknowledgement transmittedon the physical uplink shared channel scheduled in the subframe n.
 31. Amethod as claimed in claim 30, comprising receiving the firstinformation and the second information from a base station.
 32. A methodas claimed in claim 30, comprising receiving the first information froma base station and calculating the second information.
 33. A method asclaimed in claim 30, comprising receiving the first information and/orthe second information from a base station in a downlink assignmentindex contained in an uplink grant.
 34. A method as claimed in claim 30,comprising causing the feedback information to be transmitted on thephysical uplink shared channel scheduled in the subframe n.
 35. A methodas claimed in claim 30, comprising causing the feedback information tobe transmitted in a subframe which is k subframes later than thesubframe n.
 36. A method as claimed in claim 30, wherein the feedbackinformation comprises feedback information for the at least one firstsubframe and the at least one second subframe, if the at least onesecond subframe is scheduled.
 37. A method as claimed in claim 30,wherein a discontinuous transmission is provided for the at least onesubframe as the feedback information, if the at least one secondsubframe is not scheduled.
 38. A method as claimed in claim 30, whereinthe feedback information comprises hybrid automatic repeat requestinformation.
 39. A computer program product comprising a non-transitorycomputer readable medium having executable instructions thereon, whichwhen run by an apparatus are configured to provide the method of claim30.
 40. A method comprising: causing first information and secondinformation to be provided to a user equipment for determining a codebook size for an ACK/NACK codebook, the first information comprisinginformation about at least one first subframe of at least one cell forwhich feedback information is to be received, the at least one firstsubframe being no later than subframe n and the second informationcomprising information about at least one second subframe of at leastone cell for which feedback information is to be received, the at leastone second subframe being after the subframe n; wherein the firstinformation and the second information together comprise informationabout a plurality of different cells, and wherein the plurality ofdifferent cells use different uplink downlink time division duplexconfigurations; and receiving the feedback information, based on thecode book size, from the user equipment; wherein the ACK/NACK codebookis generated according to a maximum number of actually scheduled type 1downlink subframes plus a maximum number of type 2 downlink subframes,and wherein the type 1 downlink subframes comprise downlink subframes nolater than the subframe n and a corresponding positive or negativeacknowledgement received on a physical uplink shared channel scheduledin the subframe n, and wherein the type 2 downlink subframes comprisedownlink subframes later than the subframe n and the correspondingpositive or negative acknowledgement received on the physical uplinkshared channel scheduled in the subframe n.
 41. A computer programproduct comprising a non-transitory computer readable medium havingexecutable instructions thereon, which when run by an apparatus areconfigured to provide the method of claim
 40. 42. An apparatuscomprising at least one processor and at least one memory includingcomputer code for one or more programs, the at least one memory and thecomputer code configured, with the at least one processor, to cause theapparatus at least to: use first information and second information todetermine a code book size for an ACK/NACK codebook, the firstinformation comprising information about at least one first subframe ofat least one cell for which feedback information is to be transmitted,the at least one first subframe being no later than subframe n and thesecond information comprising information about at least one secondsubframe of at least one cell for which feedback information is to betransmitted, the at least one second subframe being after the subframen; wherein the first information and the second information togethercomprise information about a plurality of different cells, and whereinthe plurality of different cells use different uplink downlink timedivision duplex configurations; and causing, by the user equipment, thefeedback information, based on the code book size, to be transmitted;wherein the ACK/NACK codebook is generated according to a maximum numberof actually scheduled type 1 downlink subframes plus a maximum number oftype 2 downlink subframes, and wherein the type 1 downlink subframescomprise downlink subframes no later than the subframe n and acorresponding positive or negative acknowledgement transmitted on aphysical uplink shared channel scheduled in the subframe n, and whereinthe type 2 downlink subframes comprise downlink subframes later than thesubframe n and the corresponding positive or negative acknowledgementtransmitted on the physical uplink shared channel scheduled in thesubframe n.
 43. The apparatus as claimed in claim 42, wherein the atleast one memory and the computer code are configured with the at leastone processor to cause the apparatus to receive the first informationand the second information from a base station.
 44. The apparatus asclaimed in claim 42, wherein the at least one memory and the computercode are configured with the at least one processor to cause theapparatus to receive the first information from a base station andcalculate the second information.
 45. The apparatus as claimed in claim42, wherein the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to receive theinformation from a base station in an uplink downlink assignment index.46. The apparatus as claimed in claim 42, wherein the at least onememory and the computer code are configured with the at least oneprocessor to cause the apparatus to cause the feedback information to betransmitted on a physical uplink shared channel scheduled in subframe n.47. The apparatus as claimed in claim 42, wherein the at least onememory and the computer code are configured with the at least oneprocessor to cause the apparatus to cause feedback information to betransmitted in a subframe which is k subframes later than subframe n.48. The apparatus as claimed in claim 42, wherein the feedbackinformation comprises feedback information for the at least one firstsubframe and the at least one second subframe, if the at least onesecond subframe is scheduled.
 49. The apparatus as claimed in claim 42,wherein the at least one memory and the computer code are configuredwith the at least one processor to cause the apparatus to provide adiscontinuous transmission for the at least one subframe as the feedbackinformation, if the at least one second subframe is not scheduled. 50.The apparatus as claimed in claim 42, wherein the feedback informationcomprises hybrid automatic repeat request information.
 51. A userequipment comprising the apparatus as claimed in claim
 42. 52. Anapparatus, comprising at least one processor and at least one memoryincluding computer code for one or more programs, the at least onememory and the computer code configured, with the at least oneprocessor, to cause the apparatus at least to: cause first informationand second information to be provided to a user equipment fordetermining a code book size for an ACK/NACK codebook, the firstinformation comprising information about at least one first subframe ofat least one cell for which feedback information is to be received, theat least one first subframe being no later than subframe n and thesecond information comprising information about at least one secondsubframe of at least one cell for which feedback information is to bereceived, the at least one second subframe being after the subframe n;wherein the first information and the second information togethercomprise information about a plurality of different cells, and whereinthe plurality of different cells use different uplink downlink timedivision duplex configurations; and receive the feedback information,based on the code book size, from the user equipment; wherein theACK/NACK codebook is generated according to a maximum number of actuallyscheduled type 1 downlink subframes plus a maximum number of type 2downlink subframes, and wherein the type 1 downlink subframes comprisedownlink subframes no later than the subframe n and a correspondingpositive or negative acknowledgement received on a physical uplinkshared channel scheduled in the subframe n, and wherein the type 2downlink subframes comprise downlink subframes later than the subframe nand the corresponding positive or negative acknowledgement received onthe physical uplink shared channel scheduled in the subframe n.
 53. Abase station comprising the apparatus as claimed in claim
 52. 54. Amethod comprising: causing first information to be provided to a userequipment for determining, along with second information, a code booksize for an ACK/NACK codebook, the first information comprisinginformation about at least one first sub frame of at least one cell forwhich feedback information is to be received, the at least one firstsubframe being no later than subframe n and the second informationcomprising information about at least one second subframe of at leastone cell for which feedback information is to be received, the at leastone second subframe being after the sub frame n; wherein the firstinformation and the second information together comprise informationabout a plurality of different cells, and wherein the plurality ofdifferent cells use different uplink downlink time division duplexconfigurations; and receiving the feedback information, based on thecode book size, from the user equipment; wherein the ACK/NACK codebookis generated according to a maximum number of actually scheduled type 1downlink subframes plus a maximum number of type 2 downlink subframes,and wherein the type 1 downlink subframes comprise downlink sub framesno later than the subframe n and a corresponding positive or negativeacknowledgement received on a physical uplink shared channel scheduledin the subframe n, and wherein the type 2 downlink subframes comprisedownlink subframes later than the subframe n and the correspondingpositive or negative acknowledgement received on the physical uplinkshared channel scheduled in the subframe n.
 55. A computer programproduct comprising a non-transitory computer readable medium havingexecutable instructions thereon, which when run by an apparatus areconfigured to provide the method of claim
 54. 56. An apparatuscomprising at least one processor and at least one memory includingcomputer code for one or more programs, the at least one memory and thecomputer code configured, with the at least one processor, to cause theapparatus at least to: cause first information to be provided to a userequipment for determining, along with second information, a code booksize for an ACK/NACK codebook, the first information comprisinginformation about at least one first subframe of at least one cell forwhich feedback information is to be received, the at least one firstsubframe being no later than subframe n and the second informationcomprising information about at least one second subframe of at leastone cell for which feedback information is to be received, the at leastone second subframe being after the subframe n; wherein the firstinformation and the second information together comprise informationabout a plurality of different cells, and wherein the plurality ofdifferent cells use different uplink downlink time division duplexconfigurations; and receive the feedback information, based on the codebook size, from the user equipment; wherein the ACK/NACK codebook isgenerated according to a maximum number of actually scheduled type 1downlink subframes plus a maximum number of type 2 downlink subframes,and wherein the type 1 downlink subframes comprise downlink subframes nolater than the subframe n and a corresponding positive or negativeacknowledgement received on a physical uplink shared channel scheduledin the subframe n, and wherein the type 2 downlink subframes comprisedownlink subframes later than the subframe n and the correspondingpositive or negative acknowledgment received on the physical uplinkshared channel scheduled in the subframe n.